I'd suggest actually changing the world first, and then shouting it from the rooftops. It will be (slightly) less annoying that way.
Besides, I'm not even sure it's a healthy sentiment for most people (http://www.sciencedaily.com/releases/2013/07/130708103509.ht...). If your focus is as broad as "changing the world," you're probably setting yourself up to feel like a failure.
It's either that or the perennial favorite, "exciting".